Clinicopathological features of non-carcinoid malignant epithelial appendix tumors and risk factors for recurrence, single-center experience.

Abstract

Non-carcinoid appendix epithelial tumors are rare. These tumors include low-grade and high-grade mucinous neoplasm also adenocarcinomas. We aimed to investigate the clinicopathological features, treatment, and risk factors of recurrence. Patients diagnosed between 2008 and 2019 were retrospectively analyzed. Categorical variables were expressed as percentages and compared using the Chi-square test or Fisher's exact tests. Overall survival and Disease-free survival of the groups were calculated by the Kaplan-Meier method, and the log-rank test was used to compare the survival rates. A total of 35 patients were included in the study. Of the patients, 19 (54%) were women and the median diagnosis age of patients was 50.4 years (19-76). As for pathological types, a total of 14 (40%) patients were mucinous adenocarcinoma and 14 (40%) patients were Low-Grade Mucinous Neoplasm (LGMN). Lymph node excision and lymph node involvement were 23 (65%) and 9 (25%) patients respectively. The majority of patients were stage 4 (27, 79%) and 25 (71%) of these patients had peritoneal metastasis. A total of 48.6% patients had been treated with cytoreductive surgery and hyper-thermic intraperitoneal chemotherapy. Median Peritoneal cancer index value was 12 (2-36). The median follow-up time was 20 (1-142) months. Recurrence developed in 12 (34%) of patients. When risk factors for recurrence are considered, there was a statistically significant difference in appendix tumors with high-grade, adenocarcinoma pathology, ones with peritoneal cancer index ≥12 and not having pseudomyxoma peritonei. Median disease-free survival was 18 (13-22, 95% CI) months. Median overall survival could not be reached while the 3-year survival rate was 79%. The risk of recurrence is higher in high-grade appendix tumors, having peritoneal cancer index ≥ 12, not having pseudomyxoma peritonei and adenocarcinoma pathology. High-grade appendix adenocarcinoma patients should be followed closely for recurrence.